%I #5 Jun 13 2015 00:51:32
%S 1,-2,4,-4,0,16,-48,96,-128,64,256,-1024,2304,-3584,3072,3072,-20480,
%T 53248,-94208,106496,0,-376832,1179648,-2359296,3211264,-1703936,
%U -6029312,24903680,-56623104,89128960,-78643200,-69206016
%N a(n)=-2a(n-1)+4a(n-3).
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (-2,0,4).
%F G.f.: 1/(1+2x-4x^3); a(n)=A099212(n+4)/4.
%K easy,sign
%O 0,2
%A _Paul Barry_, Oct 06 2004